Lacunaryx: computing bounded-degree factors of lacunary polynomials. In this paper, we report on an implementation in the free software Mathemagix of lacunary factorization algorithms, distributed as a library called Lacunaryx. These algorithms take as input a polynomial in sparse representation, that is as a list of nonzero monomials, and an integer d, and compute its irreducible degree-≤d factors. The complexity of these algorithms is polynomial in the sparse size of the input polynomial and d.